Writing shows that you're alive. It doesn't matter whether you can write like Shakespeare or Tennyson or Hemingway. Words are merely a medium to express your thoughts, your ideas.
When you write you are putting your ideas and thoughts down to be shared with another being, even if it is God. It concretizes what's been floating in your head, it clarifies your vision, it sharpens your ideas.
Writing doesn't have to be perfect.. it can be in spurts.. bits.. pieces. Fragments.
Whatever comes to your mind. The more you write the better you get at it.
Review what you write once in a while, read what you wrote. You can see how you've grown and become better over the years.